<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	https://codeigniter.com
 * @since	Version 1.0.0
 * @filesource
 */
defined('BASEPATH') or exit('No direct script access allowed');

/**
 * Trackback Class
 *
 * Trackback Sending/Receiving Class
 *
 * @package CodeIgniter
 * @subpackage Libraries
 * @category Trackbacks
 * @author EllisLab Dev Team
 * @link https://codeigniter.com/user_guide/libraries/trackback.html
 */
class CI_Trackback
{

    /**
     * Character set
     *
     * @var string
     */
    public $charset = 'UTF-8';

    /**
     * Trackback data
     *
     * @var array
     */
    public $data = array(
        'url' => '',
        'title' => '',
        'excerpt' => '',
        'blog_name' => '',
        'charset' => ''
    );

    /**
     * Convert ASCII flag
     *
     * Whether to convert high-ASCII and MS Word
     * characters to HTML entities.
     *
     * @var bool
     */
    public $convert_ascii = TRUE;

    /**
     * Response
     *
     * @var string
     */
    public $response = '';

    /**
     * Error messages list
     *
     * @var string[]
     */
    public $error_msg = array();
    
    // --------------------------------------------------------------------
    
    /**
     * Constructor
     *
     * @return void
     */
    public function __construct()
    {
        log_message('info', 'Trackback Class Initialized');
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Send Trackback
     *
     * @param
     *            array
     * @return bool
     */
    public function send($tb_data)
    {
        if (! is_array($tb_data)) {
            $this->set_error('The send() method must be passed an array');
            return FALSE;
        }
        
        // Pre-process the Trackback Data
        foreach (array(
            'url',
            'title',
            'excerpt',
            'blog_name',
            'ping_url'
        ) as $item) {
            if (! isset($tb_data[$item])) {
                $this->set_error('Required item missing: ' . $item);
                return FALSE;
            }
            
            switch ($item) {
                case 'ping_url':
                    $$item = $this->extract_urls($tb_data[$item]);
                    break;
                case 'excerpt':
                    $$item = $this->limit_characters($this->convert_xml(strip_tags(stripslashes($tb_data[$item]))));
                    break;
                case 'url':
                    $$item = str_replace('&#45;', '-', $this->convert_xml(strip_tags(stripslashes($tb_data[$item]))));
                    break;
                default:
                    $$item = $this->convert_xml(strip_tags(stripslashes($tb_data[$item])));
                    break;
            }
            
            // Convert High ASCII Characters
            if ($this->convert_ascii === TRUE && in_array($item, array(
                'excerpt',
                'title',
                'blog_name'
            ), TRUE)) {
                $$item = $this->convert_ascii($$item);
            }
        }
        
        // Build the Trackback data string
        $charset = isset($tb_data['charset']) ? $tb_data['charset'] : $this->charset;
        
        $data = 'url=' . rawurlencode($url) . '&title=' . rawurlencode($title) . '&blog_name=' . rawurlencode($blog_name) . '&excerpt=' . rawurlencode($excerpt) . '&charset=' . rawurlencode($charset);
        
        // Send Trackback(s)
        $return = TRUE;
        if (count($ping_url) > 0) {
            foreach ($ping_url as $url) {
                if ($this->process($url, $data) === FALSE) {
                    $return = FALSE;
                }
            }
        }
        
        return $return;
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Receive Trackback Data
     *
     * This function simply validates the incoming TB data.
     * It returns FALSE on failure and TRUE on success.
     * If the data is valid it is set to the $this->data array
     * so that it can be inserted into a database.
     *
     * @return bool
     */
    public function receive()
    {
        foreach (array(
            'url',
            'title',
            'blog_name',
            'excerpt'
        ) as $val) {
            if (empty($_POST[$val])) {
                $this->set_error('The following required POST variable is missing: ' . $val);
                return FALSE;
            }
            
            $this->data['charset'] = isset($_POST['charset']) ? strtoupper(trim($_POST['charset'])) : 'auto';
            
            if ($val !== 'url' && MB_ENABLED === TRUE) {
                if (MB_ENABLED === TRUE) {
                    $_POST[$val] = mb_convert_encoding($_POST[$val], $this->charset, $this->data['charset']);
                } elseif (ICONV_ENABLED === TRUE) {
                    $_POST[$val] = @iconv($this->data['charset'], $this->charset . '//IGNORE', $_POST[$val]);
                }
            }
            
            $_POST[$val] = ($val !== 'url') ? $this->convert_xml(strip_tags($_POST[$val])) : strip_tags($_POST[$val]);
            
            if ($val === 'excerpt') {
                $_POST['excerpt'] = $this->limit_characters($_POST['excerpt']);
            }
            
            $this->data[$val] = $_POST[$val];
        }
        
        return TRUE;
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Send Trackback Error Message
     *
     * Allows custom errors to be set. By default it
     * sends the "incomplete information" error, as that's
     * the most common one.
     *
     * @param
     *            string
     * @return void
     */
    public function send_error($message = 'Incomplete Information')
    {
        exit('<?xml version="1.0" encoding="utf-8"?' . ">\n<response>\n<error>1</error>\n<message>" . $message . "</message>\n</response>");
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Send Trackback Success Message
     *
     * This should be called when a trackback has been
     * successfully received and inserted.
     *
     * @return void
     */
    public function send_success()
    {
        exit('<?xml version="1.0" encoding="utf-8"?' . ">\n<response>\n<error>0</error>\n</response>");
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Fetch a particular item
     *
     * @param
     *            string
     * @return string
     */
    public function data($item)
    {
        return isset($this->data[$item]) ? $this->data[$item] : '';
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Process Trackback
     *
     * Opens a socket connection and passes the data to
     * the server. Returns TRUE on success, FALSE on failure
     *
     * @param
     *            string
     * @param
     *            string
     * @return bool
     */
    public function process($url, $data)
    {
        $target = parse_url($url);
        
        // Open the socket
        if (! $fp = @fsockopen($target['host'], 80)) {
            $this->set_error('Invalid Connection: ' . $url);
            return FALSE;
        }
        
        // Build the path
        $path = isset($target['path']) ? $target['path'] : $url;
        empty($target['query']) or $path .= '?' . $target['query'];
        
        // Add the Trackback ID to the data string
        if ($id = $this->get_id($url)) {
            $data = 'tb_id=' . $id . '&' . $data;
        }
        
        // Transfer the data
        fputs($fp, 'POST ' . $path . " HTTP/1.0\r\n");
        fputs($fp, 'Host: ' . $target['host'] . "\r\n");
        fputs($fp, "Content-type: application/x-www-form-urlencoded\r\n");
        fputs($fp, 'Content-length: ' . strlen($data) . "\r\n");
        fputs($fp, "Connection: close\r\n\r\n");
        fputs($fp, $data);
        
        // Was it successful?
        
        $this->response = '';
        while (! feof($fp)) {
            $this->response .= fgets($fp, 128);
        }
        @fclose($fp);
        
        if (stripos($this->response, '<error>0</error>') === FALSE) {
            $message = preg_match('/<message>(.*?)<\/message>/is', $this->response, $match) ? trim($match[1]) : 'An unknown error was encountered';
            $this->set_error($message);
            return FALSE;
        }
        
        return TRUE;
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Extract Trackback URLs
     *
     * This function lets multiple trackbacks be sent.
     * It takes a string of URLs (separated by comma or
     * space) and puts each URL into an array
     *
     * @param
     *            string
     * @return string
     */
    public function extract_urls($urls)
    {
        // Remove the pesky white space and replace with a comma, then replace doubles.
        $urls = str_replace(',,', ',', preg_replace('/\s*(\S+)\s*/', '\\1,', $urls));
        
        // Break into an array via commas and remove duplicates
        $urls = array_unique(preg_split('/[,]/', rtrim($urls, ',')));
        
        array_walk($urls, array(
            $this,
            'validate_url'
        ));
        return $urls;
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Validate URL
     *
     * Simply adds "http://" if missing
     *
     * @param
     *            string
     * @return void
     */
    public function validate_url(&$url)
    {
        $url = trim($url);
        
        if (stripos($url, 'http') !== 0) {
            $url = 'http://' . $url;
        }
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Find the Trackback URL's ID
     *
     * @param
     *            string
     * @return string
     */
    public function get_id($url)
    {
        $tb_id = '';
        
        if (strpos($url, '?') !== FALSE) {
            $tb_array = explode('/', $url);
            $tb_end = $tb_array[count($tb_array) - 1];
            
            if (! is_numeric($tb_end)) {
                $tb_end = $tb_array[count($tb_array) - 2];
            }
            
            $tb_array = explode('=', $tb_end);
            $tb_id = $tb_array[count($tb_array) - 1];
        } else {
            $url = rtrim($url, '/');
            
            $tb_array = explode('/', $url);
            $tb_id = $tb_array[count($tb_array) - 1];
            
            if (! is_numeric($tb_id)) {
                $tb_id = $tb_array[count($tb_array) - 2];
            }
        }
        
        return ctype_digit((string) $tb_id) ? $tb_id : FALSE;
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Convert Reserved XML characters to Entities
     *
     * @param
     *            string
     * @return string
     */
    public function convert_xml($str)
    {
        $temp = '__TEMP_AMPERSANDS__';
        
        $str = preg_replace(array(
            '/&#(\d+);/',
            '/&(\w+);/'
        ), $temp . '\\1;', $str);
        
        $str = str_replace(array(
            '&',
            '<',
            '>',
            '"',
            "'",
            '-'
        ), array(
            '&amp;',
            '&lt;',
            '&gt;',
            '&quot;',
            '&#39;',
            '&#45;'
        ), $str);
        
        return preg_replace(array(
            '/' . $temp . '(\d+);/',
            '/' . $temp . '(\w+);/'
        ), array(
            '&#\\1;',
            '&\\1;'
        ), $str);
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Character limiter
     *
     * Limits the string based on the character count. Will preserve complete words.
     *
     * @param
     *            string
     * @param
     *            int
     * @param
     *            string
     * @return string
     */
    public function limit_characters($str, $n = 500, $end_char = '&#8230;')
    {
        if (strlen($str) < $n) {
            return $str;
        }
        
        $str = preg_replace('/\s+/', ' ', str_replace(array(
            "\r\n",
            "\r",
            "\n"
        ), ' ', $str));
        
        if (strlen($str) <= $n) {
            return $str;
        }
        
        $out = '';
        foreach (explode(' ', trim($str)) as $val) {
            $out .= $val . ' ';
            if (strlen($out) >= $n) {
                return rtrim($out) . $end_char;
            }
        }
    }
    
    // --------------------------------------------------------------------
    
    /**
     * High ASCII to Entities
     *
     * Converts Hight ascii text and MS Word special chars
     * to character entities
     *
     * @param
     *            string
     * @return string
     */
    public function convert_ascii($str)
    {
        $count = 1;
        $out = '';
        $temp = array();
        
        for ($i = 0, $s = strlen($str); $i < $s; $i ++) {
            $ordinal = ord($str[$i]);
            
            if ($ordinal < 128) {
                $out .= $str[$i];
            } else {
                if (count($temp) === 0) {
                    $count = ($ordinal < 224) ? 2 : 3;
                }
                
                $temp[] = $ordinal;
                
                if (count($temp) === $count) {
                    $number = ($count === 3) ? (($temp[0] % 16) * 4096) + (($temp[1] % 64) * 64) + ($temp[2] % 64) : (($temp[0] % 32) * 64) + ($temp[1] % 64);
                    
                    $out .= '&#' . $number . ';';
                    $count = 1;
                    $temp = array();
                }
            }
        }
        
        return $out;
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Set error message
     *
     * @param
     *            string
     * @return void
     */
    public function set_error($msg)
    {
        log_message('error', $msg);
        $this->error_msg[] = $msg;
    }
    
    // --------------------------------------------------------------------
    
    /**
     * Show error messages
     *
     * @param
     *            string
     * @param
     *            string
     * @return string
     */
    public function display_errors($open = '<p>', $close = '</p>')
    {
        return (count($this->error_msg) > 0) ? $open . implode($close . $open, $this->error_msg) . $close : '';
    }
}
